The present invention relates generally to the treatment of agricultural waste. More particularly, the present invention provides a chemical treatment method that effectively removes biological oxygen demand, chemical oxygen demand, ammonia, phosphate and solids from agricultural waste, resulting in an environmentally acceptable agri-waste.
The agricultural community faces never-ending concerns regarding the disposal and spreading of agricultural waste onto land. As new environmental legislation is enforced, the agricultural community is finding itself under increased scrutiny. Among other matters, the agricultural community is concerned with the very high pollution potential of farm slurries. The high pollution potential results from a very high biological oxygen demand ("BOD"), a high chemical oxygen demand ("COD"), as well as the ammonia content in agricultural waste.
In addition to the lowering of pollution potential, the agricultural community strives to reduce slurry volume. The reduction of slurry volume provides environmental advantages. For instance, the reduction of slurry volume can alleviate the need for large holding tanks. Moreover, since a reduced slurry volume lessens the number of times heavy machinery passes over the land, spreading is less time-consuming and less arduous on the land. Still further, the reduction of slurry volume reduces the possibility of runoff onto local water courses.
While a definite need exists for the treatment of agricultural waste, none of the present methods available adequately deal with the complete treatment and disposal of composite farm waste. For instance, some have resorted to the selling of nitric acid systems to control odor and restrict evolution of ammonia gas from storage slurries. Others have proposed the use of high pressure filtration systems in the removal of suspended solids from slurry. Still further, others are proposing the use of centrifugation of composite farm waste. However, the use of filtration and centrifugation systems have been questioned due to their high capital costs.
Yet another proposed treatment method is the use of anaerobic and aerobic digestion. While in theory such digestion methods may prove useful, they also require high capital investment. Moreover, such digestion methods do not necessarily produce environmentally acceptable outflow, and do not immediately yield material for composting.
A further concern with anaerobic and aerobic digestion is that they require large areas of space as well as technical support and service, neither of which are particularly common within agri-business. Moreover, such digestion methods are to an extent inhibited during periods of low temperature. Thus, although many have proposed different methods for treating agricultural waste, none of the proposed methods are being implemented on any significant scale.
Accordingly, the current options for waste treatment are limited. At present, farm waste is generally recycled via lagoon collection and intermittent slurry application onto land. However, as a result of the new Environmental Protection Act (1991), the National Rivers Authority Proposals for Protection of Groundwater, and the new Control of Pollution Regulations (1991), restrictions are now being placed upon how waste is collected and re-used. Conceivably, regulations will be enacted that control the use of such agricultural waste. For instance, regulations will likely place a ban on the application of waste to certain areas of top grade agricultural lands, such as soils in lowland sand and gravel outwash plains.
In the event such regulations are enacted, the agricultural waste will then have to be disposed off-site. However, even if disposal sites can be found, the shipment of slurry to off-site disposal will be expensive.
Therefore, a need exists for a treatment system that addresses all the environmental concerns presented by agricultural waste, while at the same time not involving high capital costs.